Exemplary embodiments relate to nanodevices, and more specifically to sequencing using a multiple layer structure in a nanodevice.
Recently, there has been growing interest in applying nanopores as sensors for rapid analysis of biomolecules such as Deoxyribonucleic acid (DNA), Ribonucleic acid (RNA), protein, etc. Special emphasis has been given to applications of nanopores for DNA sequencing, as this technology holds the promise to reduce the cost of sequencing below $1000/human genome. Two issues in these applications of nanopores are the control of the translocation of DNA through the nanopore and differentiating DNA bases.
Nanopore sequencing is a method for determining the order in which nucleotides occur on a strand of DNA. A nanopore is simply a small hole on the order of several nanometers in internal diameter. The theory behind nanopore sequencing has to do with what occurs when the nanopore is immersed in a conducting fluid and an electric potential (voltage) is applied across it: under these conditions a slight electric current due to conduction of ions through the nanopore can be measured, and the amount of current is very sensitive to the size and shape of the nanopore. If single bases or strands of DNA pass (or part of the DNA molecule passes) through the nanopore, this can create a change in the magnitude of the current through the nanopore. Other electrical or optical sensors can also be put around the nanopore so that DNA bases can be differentiated while the DNA passes through the nanopore.
DNA could be driven through the nanopore by using various methods. For example, an electric field might attract the DNA towards the nanopore, and it might eventually pass through it. Also, enzymes attached to the nanopore might guide DNA towards the nanopore. The scale of the nanopore means that the DNA may be forced through the hole as a long string, one base at a time, rather like thread through the eye of a needle.